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Porphyromonas gingivalis-induced glucose intolerance during periapical lesions requires its LPS throught a Th17 immune response
No full textInternational audienceThis study investigates the role of Interleukin 17 (IL-17) in exacerbating periapical lesions caused by Porphyromonas gingivalis ( Pg ) lipopolysaccharides (LPS) in the context of metabolic disease and its potential impact on glucose tolerance. Researchers developed a unique mouse model where mice were monocolonized with Pg to induce periapical lesions. After 1 month, they were fed a high-fat diet (HFD) for 2 months to simulate metabolic disease and oral microbiota dysbiosis. To explore the role of LPS from Pg , wild-type (WT) mice were challenged with purified LPS from Porphyromonas gingivalis , as well as with LPS-depleted and non-depleted Pg bacteria; IL-17 knockout (KO) mice were also included to assess the role of IL-17 signaling. The impact on bone lysis, periapical injury, glucose intolerance, and immune response was assessed. Results showed that in WT mice, the presence of LPS significantly worsened bone lysis, Th17 cell recruitment, and periapical injury. IL-17 KO mice exhibited reduced bone loss, glucose intolerance, and immune cell infiltration. Additionally, inflammatory markers in adipose tissue were lower in IL-17 KO mice, despite increased dysbiosis. The findings suggest that IL-17 plays a critical role in amplifying Pg -induced periapical lesions and systemic metabolic disturbances. Targeting IL-17 recruitment could offer a novel approach to improving glycemic control and reducing type 2 diabetes (T2D) risk in individuals with periapical disease
Multi-Physics Simulation of Void Evolution in Thermoset Prepreg UD Laminates
No full textInternational audienc
Elephants explore in spirals sometimes
No full textWe consider in this article an Elephant Random Walk evolving in the plane. Specifically, this is a reinforced stochastic process in which the nth step is given by a random rotation of one of the previous steps chosen uniformly at random. We obtain a central limit theorem for this process, which shows that the process follows a randomly rotated logarithmic spiral at large times, with Gaussian fluctuations
Coupled Local and Global World Models for Efficient First Order RL
No full textRL has demonstrated strong performance in locomotion through robust sim-toreal transfer from parallelized simulators to hardware. In contrast, extending this simulator-centric approach to real-world robotics manipulation is hindered by high data demands, sim-to-real discrepancies in intricate interactions, and the difficulty of engineering rewards or accurate physics for tasks involving deformable or irregular objects. We introduce a framework that replaces simulators with a diffusion-based world model trained on real robot image data, which captures complex dynamics from data without rule-based modeling, thus addressing the limitations that prevent simulator-style RL from succeeding in manipulation. Our method enables feasible policy training despite the high cost of trajectory unrolls in large-scale image models, through a novel decoupled first-order gradient (FoG) approach: the full world model generates accurate forward trajectories, while a lightweight latent-space surrogate model is learned to approximate local dynamics around the policy's trajectories, providing efficient, low-variance gradients via backpropagation. This surrogate operates on compressed representations, avoiding direct differentiation through pixel-level diffusion processes. Unlike previous model-based RL approaches, this decoupling ensures high-fidelity forward unrolling alongside computationally tractable backward differentiation. Evaluated on a real robotic arm, our method achieves high success rate on the Push-T task, strongly outperforming PPO in sample-and time-efficiency while offering a scalable alternative to simulator-dependent RL for real-world manipulation
Non-Hermitian topology in the quantum Hall effect of graphene
No full textQuantum Hall phases have recently emerged as a platform to investigate non-Hermitian topology in condensed-matter systems. This platform is particularly interesting due to its tunability, which allows to modify the properties and topology of the investigated non-Hermitian phases by tuning external parameters of the system such as the magnetic field. Here, we show the tunability of non-Hermitian topology chirality in a graphene heterostructure using a gate voltage. By changing the charge carrier density, we unveil some novel properties specific to different quantum Hall regimes. First, we find that the best quantization of the non-Hermitian topological invariant is interestingly obtained at very high filling factor rather than on well-quantized quantum Hall plateaus. This is of particular importance for the efficient operation of devices based on non-Hermitian topology. Moreover, we observe an additional non-Hermitian topological phase in the insulating nu=0 quantum Hall plateau, which survives at lower fields than the opening of the nu=0 gap, confirming a recent prediction of a disorder-induced trivial phase. Our results evidence graphene as a promising platform for the study of non-Hermitian physics and of emergent phases in such topological devices
Stockage et utilisation du CO2 par précipitation de carbonate de calcium induite par voie biologique dans le cycle phototrophe du soufre
No full textThis project aims to explore the potential of photosynthetic microorganisms, specifically Anoxygenic Phototrophic Sulfur Bacteria (APSB), for the treatment and valorization of CO2 and H2S present in industrial effluents or biogas. Thanks to their autotrophic metabolism, APSB offer the advantage of oxidizing H2S into sulfates while using CO2 as a carbon source, simultaneously creating favorable conditions for carbonate precipitation. This bioprecipitation of carbonates is a natural process, which amplified in an anaerobic phototrophic bioreactor, could enable the use of CO2 as a carbon source while storing it sustainably, both as biomass and precipitates.The study first focused on the growth kinetic and photoautotrophic metabolism of APSB. Batch experiments were conducted using the pure strain Allochromatium vinosum, with a synthetic inorganic nutritional medium and a continuous exposure to infrared light (LED). Inorganic carbon, sulfur species (H2S, S0, S2O32-, SO42-), some ions (NH4+, PO43-, Ca2+, etc.), chemical oxygen demand, optical density, and pH were measured to follow the growth and photoautotrophic activity of A. vinosum. The results enabled the development and calibration of a numerical model of APSB growth on various sulfur substrates, representing the evolution of nutrients and biomass. The model accurately fits the experimental data from this study and also literature data, from both pure and mixed cultures.Then abiotic calcium carbonate precipitation was studied both experimentally and numerically. Precipitation experiments were conducted under abiotic conditions close to those required for APSB growth (complex nutritional medium, alkaline pH, varying saturation index). The acquired data were used to develop a model on Aquasim software, considering different precipitation reactions, calcium carbonate polymorphs and competing precipitates such as calcium phosphates. The model reliably predicts calcium carbonate precipitation kinetics under the studied conditions.The two models were then coupled to explore the potential of APSB photoautotrophic activity in inducing calcium carbonate precipitation. To our knowledge, this is the first time such a global model has been proposed, coupling autotrophic APSB growth with carbonate bioprecipitation. Batch-mode simulations with varying initial calcium and phosphorus concentrations were performed to study biomass/precipitation competition for phosphates. Results showed that reducing initial phosphate concentration could limit calcium phosphate formation without hindering bacterial growth. Additional continuous simulations, with varying hydraulic retention time, sulfide fluxes, and a biogas injection scenario, were used to discuss the process's potential for CO2 capture.Since real-life implementation of this process is technically challenging with a pure strain, APSB selection tests were conducted. Semi-batch enrichment experiments were performed using a mixed inoculum of A. vinosum and wastewater. Apart from the inoculum, conditions were identical to those of previous culture experiments. The results showed that photoautotrophic activity remained dominant even in the presence of wastewater rich in microorganisms, which is promising for the project's next stages.Ce projet vise à explorer le potentiel de micro-organismes photosynthétiques, les bactéries phototrophes anoxygéniques sulfureuses (APSB), pour le traitement et la valorisation du CO2 et de l’H2S contenus dans des effluents industriels ou du biogaz. En effet, par leur métabolisme autotrophe, les APSB présentent l’avantage d’oxyder l’H2S sous forme de sulfates et d’utiliser le CO2 comme source de carbone, tout en induisant des conditions favorables à la précipitation des carbonates. La bioprécipitation des carbonates est un processus naturel, qui une fois amplifié dans un bioréacteur anaérobie phototrophique, pourrait permettre l’utilisation du CO2 comme source de carbone, tout en le stockant de manière stable et durable, à la fois sous forme de biomasse et de précipités.L’étude s’est d’abord concentrée sur la cinétique de croissance et le métabolisme photoautotrophique des APSB. Des expériences en mode batch de culture de la souche pure Allochromatium vinosum, ont été menées avec exposition continue à des LED infrarouge et milieu inorganique synthétique. Le carbone inorganique, les espèces soufrées (H2S, S0, S2O32-, SO4-), certains ions (NH4+, PO42-, Ca2+, etc.), la demande chimique en oxygène, la densité optique et le pH ont été mesurés pour suivre la croissance et l’activité photoautotrophe de A.vinosum. Les résultats ont permis le développement et la calibration d’un modèle numérique de la croissance des APSB sur différents substrats soufrés, représentant l’évolution des différents nutriments et de la biomasse. Il représente correctement les données de l’étude mais également des données de la littérature, qu’elles soient basées sur des cultures pures ou des cultures mixtes.L’étude s’est ensuite portée sur la précipitation abiotique des carbonates de calcium, d’un point de vue expérimental et numérique. Des expériences de précipitation ont été réalisées dans différentes conditions abiotiques proches de celles nécessaires à la croissance des APSB (milieu nutritif complexe, pH alcalin, différents indices de saturation) et les données acquises ont permis la conception d’un modèle sur le logiciel Aquasim. Ce modèle prend en compte différentes réactions de précipitation et polymorphes de carbonates de calcium, ainsi que d’autres précipités pouvant rentrer en compétition avec la précipitation des carbonates de calcium, comme les phosphates de calcium. Le modèle développé permet une bonne prédiction des cinétiques de précipitation des carbonates de calcium dans les conditions de l’étude.Les deux modèles ont donc été couplés afin d’explorer le potentiel de l’activité photoautotrophique des APSB pour induire la précipitation de carbonates de calcium. À notre connaissance, c’est la première fois qu’un tel modèle global est proposé pour la croissance autotrophe des APSB couplé à la bioprécipitation des carbonates. Des simulations ont été faites en mode batch avec différentes concentrations initiales en calcium et phosphore afin d’étudier la compétition biomasse/précipitation pour l’accès aux phosphates et ont montré qu’une diminution des phosphates permettrait de limiter la formation de phosphates de calcium sans limiter la croissance des bactéries. D’autres simulations en continu avec variation de temps de séjour, du flux de sulfures et projection d’un scénario avec injection de biogaz ont permis de discuter du potentiel de ce procédé pour la capture de CO2.Un tel procédé ne pouvant pas être mis en pratique avec une souche pure pour des raisons techniques, des tests de sélection d’APSB ont été mis en œuvre. Des expériences d’enrichissement en semi-batch ont été faites avec un mélange A.vinosum:eaux usées comme inoculum. Hormis l’inoculum, des conditions identiques aux premières expériences présentées dans cette étude ont été appliquées. Les résultats obtenus ont montré que même en présence d’eaux usées riches en micro-organismes, l’activité photoautotrophique reste dominante, ce qui est prometteur pour la suite du projet
Analysis of a non-LTE hypersonic spectrum of methane between 5880 and 6220 cm−1
No full textInternational audienceThe SMAUG device is used to thermally populate the vibrational states of the methane molecule and depopulate its rotational states through its supersonic expansion in argon. The methane molecule is probed during expansion by cavity ringdown spectroscopy (CRDS) between 5880 and 6220 cm -1 . The laser beam passes through both the isentropic core of the flow, characterized by a very low rotational temperature of 40.4 0.8 K, and the hotter boundary layers surrounding it, which are characterized by an average rotational temperature of 364.3 7.7 K. Analysis of the spectrum reveals that the vibrational population does not follow a Boltzmann distribution. A special procedure is developed to assign an effective vibrational temperature to each vibrational state, ranging from 532.4 32.2 to 1112.0 81.7 K for molecules in the isentropic core, and from 811.6 43.1 to 851.8 45.6 K for those in the shear layer. Only the first vibrational states of each methane polyad remain significantly populated leading to detectable transitions. A total of 2347 transitions from the cold gas of the isentropic core and from the warmer gas of the boundary layers are assigned from a new ab initio effective model and 749 are confirmed by lower state combination differences (LSCD). Among these transitions, 694 originates from cold bands and 1653 from hot bands starting from vibrational states 4, 2 (dyad), 24 (pentad) and 34 (octad).</div
Electroreduction of water, a promising alternative to gas injection: A case on hydrogen solubilization in biological processes involving hydrogenotrophs
No full textInternational audienceHydrogenotrophic microorganisms reduce organic or inorganic molecules coupled with the oxidation of H 2 , for the production of valuable products such as carboxylic acids, methane, and ethanol, as well as the reduction of sulfates, nitrates or iron for remediation applications. H 2 is usually dissolved by gas injection but the low gas-toliquid mass transfer limits its biotic uptake. This study proposes water electroreduction (WE) as an alternative to gas injection (GI) for dissolving H 2 . First, WE and GI were compared in terms of H 2 solubilization rate, efficiency, and maximum dissolved concentration in a 0.8 L potassium phosphate buffered medium (0.1 mol⋅L -1 , pH = 7.2) used as a representative medium for the enrichment and study of hydrogenotrophic microorganisms. Although the H 2 production rate of WE was around 18 times lower than the H 2 supply rate used during GI, both techniques achieved similar H 2 solubilization rate but different solubilization efficiencies. To reach a solubilization rate of 0.67 mmol⋅L -1 ⋅h -1 by WE, 1.87 mmol⋅h -1 of H 2 were produced, yielding a 35 % solubilization efficiency. In contrast, achieving a comparable solubilization rate of 0.79 mmol⋅L -1 ⋅h -1 via GI required an injection of 42 mmol⋅h -1 , corresponding to a solubilization efficiency of only 2 %. Moreover, the maximum concentration of dissolved H 2 reached (0.62 mmol⋅L -1 ) by GI was limited by the saturation concentration at 1 bar (0.78 mmol⋅L -1 ), while by WE it reached 1.21 mmol⋅L -1 . WE holds strong potential as a H 2 source for biological processes involving hydrogenotrophs where high H 2 concentrations are desirable to enhance metabolite production rates and selectivity
Fractional Digital Regenerative Frequency Dividers
No full textInternational audienceABSTRACT This paper describes the topology and operation of a new family of asynchronous frequency dividers called fractional digital regenerative frequency dividers. The operation is explained using a digital approach in the time domain compared to the more classical analogue approach in the frequency domain. A fractional behaviour is intrinsic to this topology without the mandatory need of an external modulator. Integer ratios can also be easily obtained, for example to serve as multi‐modulus dividers when required. Starting with the elementary version of this kind of divider, a generalization is made with repeated cell patterns in the closed loop for finer control of the fractional ratio. Some measurements on an FPGA‐based implementation are provided to validate the division ratio of the elementary version as well as an example of a more complex configuration
Simulation numérique de l'écoulement de la résine dans un milieu poreux double-échelle : prise en compte des effets capillaires
No full textInternational audienceSimulation numérique de l'écoulement de la résine dans un milieu poreux double-échelle : prise en compte des effets capillaire